This invention relates to a method and apparatus for scarifying a railroad crib. More specifically, the invention provides for removal of ballast from in between adjacent railroad ties.
It is necessary to recondition railroad track beds from time to time. As part of this process, a cribbing operation is often performed. The cribbing operation occurs after a rail and its associated tie plates and rail anchors are removed from their normal location adjacent one side of the railroad ties.
The cribbing operation itself involves cleaning off the area of the ties on which the tie plates associated with the moved rail had been located. This allows for the later smoothing of the top of the tie for placement of new or recycled tie plates. Additionally, the cribbing operation requires the removal of ballast from in between the ties to provide room for the rail anchors. These anchors, as well known in the art, clip underneath the rail and bear against the sides of the ties to minimize creeping, expansion, or other movement of the continuous welded rail.
Rotary sweeping cores with a plurality of brush elements or bristles have typically been used for cribbing. Such brush elements are disclosed in my prior U.S. Pat. No. Re. 31,619, issued July 3, 1984 and entitled "SWEEPER BRISTLE AND METHOD OF MAKING". Although the brush elements may be mounted upon a rotary sweeper which rotates about an axis parallel to the ties for simply cleaning ties and evenly distributing the ballast, the cribbing operation uses the brush elements mounted for rotation on a sweeper core having a rotation axis perpendicular to the railroad ties. The brush elements are sufficiently flexible to bend as they sweep across a railroad tie, whereas they extend below the upper surfaces of the ties and dig or sweep ballast material out from in between the ties.
A problem in the cribbing operation is that certain types of ballast may be ground into quite fine particles. When it rains, the fine particles may set up like concrete such that it is too hard for flexible sweeper or brush elements to remove the ballast. Accordingly, some prior art machines having rotary sweeping cores for cribbing have also included scarifiers.
Typically, a prior art scarifier as used in cribbing has been a solid wheel with a number of hammer or digger teeth removably fixed at the periphery of the wheel. The teeth may be standard coal mining bits. As the vehicle having the cribbing sweeper and scarifier is moved along a railroad bed, an operator uses a control to lower the rotatable scarifying wheel between the ties. The operator must raise and lower the scarifier wheel in between each pair of adjacent ties which have the hardened ballast. The scarifier wheel rotates such that its teeth hammer against and dig into the hardened ballast. When the machine comes upon a section of the railroad bed which does not have the hardened ballast, the operator may simply maintain the scarifier wheel in an upper position away from the track bed. Sweeper elements may be disposed before and/or after the scarifier wheel, typically as part of the same vehicle.
Although the prior art cribbing scarifiers have been generally useful, they have been subject to a number of disadvantages. In particular, they have required an operator who raises and lowers the scarifier wheel in between each pair of adjacent ties as necessary to break cemented or hardened ballast. The operator either has to stop the machine to lower the scarifier wheel or, alternately, may lower the scarifier wheel when the machine or vehicle is moving sufficiently slow. If an operator tries to move the vehicle too quickly, the scarifier wheel will either not sufficiently break up the ballast (when the scarifier wheel remained in its lower position for too short a time) or strike a tie with its hammer teeth (when the scarifier wheel was maintained in its lower position for too long a time).
In addition to causing incomplete breakage of the hardened ballast and damage to ties, and requiring the additional labor cost of an operator to raise and lower the scarifier wheel in between adjacent ties, the prior art type of scarifier wheel is relatively slow in operation. That is, the operator who is concerned about properly breaking the hardened ballast without damaging the ties must run the vehicle at a relatively slow speed in order to minimize errors.
In the divergent area of cutting bushes and/or trimming trees, cutting wheels with knives pivotably mounted to the wheels have been used. The knives are extended by centrifugal force such that they will swing away from anything which is too hard or too thick for the knives to cut through it.